The first man-made object to land on Mars arrived 40 years ago this month, and NASA's Curiosity rover should soon depart for the Red Planet. Here is a look at where humankind's many Mars landers have touched down, and where the planet betrays a history of all-important liquid water. Find out more in Exploring the Red Planet

Without a firm destination, will NASA's ambitions for a return to manned spaceflight beyond Earth orbit founder? Or, will scrapping the Constellation Program give the U.S. more options for human exploration of the moon, Mars and the asteroids?

Despite a gummed up drill bit and three days of very un-Martian precipitation, engineers pronounced the test a success--and learned to expect the unexpected, whether it be in the California outback or on Mars